Regulation of CYP4F2 leukotriene B4 omega-hydroxylase by retinoic acids in HepG2 cells.
Alitretinoin; Antineoplastic Agents/*pharmacology; Cultured; Cytochrome P-450 Enzyme System/*genetics/metabolism; Cytochrome P450 Family 4; Enzymologic/*drug effects; Gene Expression Regulation; Humans; Hydroxylation; Leukotriene B4/metabolism; Molecular Sequence Data; Tretinoin/*pharmacology; Tumor Cells; Up-Regulation
The human CYP4F2 gene encodes a LTB4 omega-hydroxylase P450 prominently expressed in liver and kidney that functions to metabolize and inactivate the pro-inflammatory eicosanoids, LTB4 and arachidonic acid. HepG2 cells transfected with CYP4F2 -506/-6 or -1727/-6 promoter reporter constructs and treated with either all-trans (AT) or 9-cis-retinoic (9cRA) showed a 2.5-fold increase in reporter activity. The P4504F2 protein content in HepG2 cells treated with 9cRA increased 2.5-fold, but not with ATRA. Dose response and time course studies revealed that 10 microM 9cRA stimulated promoter activity 10-fold at 12 h while 20 microM ATRA increased activity 2.5-fold after 48 h. Cotransfection with RXRalpha can enhance reporter activity 2.5-fold, while RXRalpha/RARalpha increased activity 1.5-fold. In contrast, cotransfection with RARalpha decreased reporter activity by retinoic acid 30%. Three regions in the CYP4F2 gene are responsive to retinoic acid with the DR1 RARE element (CCTCCT G TGACCT) at -708 able to bind RXRalpha/RARalpha heterodimers and mediate the repressive response of ATRA. These results indicate that retinoic acid can regulate CYP4F2 gene activity with RXRalpha heterodimers stimulating while RARalpha functioning to repress CYP4F2 gene expression.
Zhang X; Hardwick J P
Biochemical and biophysical research communications
2000
2000-12
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1006/bbrc.2000.4020" target="_blank" rel="noreferrer noopener">10.1006/bbrc.2000.4020</a>
CDNA-DIRECTED EXPRESSION OF HUMAN CYTOCHROME-P450 CYP3A4 USING BACULOVIRUS
pharmacokinetics; Pharmacology & Pharmacy; metabolism; polymorphism; identification; reductase; oxidation; vaccinia virus; human-liver; catalytic activities; hydroxylation
A recombinant baculovirus containing the human CYP3A4 cDNA was constructed and used to express CYP3A4 in SF9 insect cells (0.46 +/- 0.13 nmol/mg protein, 103 +/- 29 nmol/liter, N = 15). The enzyme represented similar to 2-3% of total cellular protein and could be purified by a two column procedure to a specific content of 12.7 nmol/mg protein. Catalytic activity of the purified enzyme after reconstitution was optimum using molar ratios of CYP3A4 to cytochrome b(5) to NADPH-P450 oxidoreductase of 1:3:20, respectively. The enzyme metabolized cortisol, erythromycin, testosterone, and (R)-warfarin. Recombinant baculovirus expresses the highest amounts of all expression systems published to date of catalytically intact CYP3A4. This system is an excellent alternative for the isolation and characterization of P450 forms from human liver.
Buters J T M; Korzekwa K R; Kunze K L; Omata Y; Hardwick J P; Gonzalez F J
Drug Metabolism and Disposition
1994
1994-09
Journal Article or Conference Abstract Publication
n/a